Metal processing compositions and method



United States Patent O 3,369,930 METAL PROCESSHNG COMPOSITIONS ANDMETHOD Wesley I. Wojtowicz, Detroit, Mich, assignor to The-H. A.Montgomery Company, Detroit, Mich., a corporation of Michigan NoDrawing. Filed Dec. 6, 1963, Ser. No. 328,507

18 Claims. (Cl. 117-134) I ABSTRACT OF THE DISCLOSURE As a metal workinglubricant, a mixture of lubricating oil of 1,500l0,000 S.U.S. at 100 F.and a water-soluble organic amine soap of low titer fatty acid, blendedin proportions of 34-75 parts of oil to 6625 parts of soap by weight. Afilm of the lubricant composition of the invention, at a temperature of50-400 F., is applied to metal stock with or without removal ofpreviously applied mill oil. Application may be effected by rollcoating,spraying, dipping, doctoring, or other means, roll-coating beingpreferred. After dissipation of any residual heatin the coating byexposure to ambient temperatures, the coated metal sheet is subjected tometal- Working operations, such as deep-drawing, to form a fabricatedarticle. Welding and painting of the deformed workpiece are performedwithout removing residual lubricant film; or the lubricant film may beremoved by using conventional alkali or acid phosphate cleaners or vapordegreasers to expose polished surfaces of the metal.

Some of the prior compositions for coating metals prior to metal workingoperations required removal before major subassemblies of parts could bemade therefrom because the prior coatings interfered with welding. Itwill be readily understood that a new process otherwise as good as suchold process, but not requiring removal of the coating prior to welding,would provide a substantial advance in the art.

Should the later development also make it possible to store componentsfor extended periods without corrosionprior to making the weldedsub-assembly-the advantages over the prior art would be still greater.

A still further advance in the art would be provided by a deep-drawlubricant that embodied all of the favorable characteristics of theprior art but, additionally, was compatible with primer paints and,therefore, need not be removed at all in the course of converting theWelded subassembly into a finished, painted product.

A general object of the present invention is to provide a noveldeep-draw formulation for the metal processing industry and a newprocedure for using such formulation.

More specific objects are to provide a novel, deep-draw, metalworkingcomposition that provides a coating for metals, the coating having thefollowing characteristics:

(a) adhesiveness to metal surfaces, obviating pre-clean- (b) lubricationof both the metal surface and the draw dies for metalworking operations;

() compatibility with additional die lubricants for deepdrawing and thelike;

(d) requiring no heat for drying the applied coating;

(e) provision of corrosion protection during extended storage ofdeep-drawn parts;

(f) no interference with welding of drawn parts; and

(g) no interference with painting of drawn parts.

A further object is to provide an improved article of manufacture, towit, a metal surface having a coating 3,369,930 Patented Feb. 20, 1968thereon which protects it before, during and, after coldworking.

THE COMPOSITIONS OF INVENTION Compositions made in accordance with thepresent invention, for producing the coatings of the invention, arenonaqueous. They consist essentially of a lubricating oil having aviscosity in the range of 1,500 to 10,000 S.U.S. at F. and awater-soluble alkanol amine soap of low titer fatty acid in proportionsof 34-75 parts of oil to 66-25 parts of amine soap, by weight. A typicalcomposition would comprise the following:

Ingredient: Percent by weight Mineral oil, 5000 S.U.S. at 100 F 66Organic amine soap 34 The character of both the oil and the soap isfurther defined below.

Preparation of the above composition merely requires blending theingredients in the amounts indicated at ambient temperatures. Thephysical appearance of the product so produced is a heavy, highlyviscous, greaselike material.

Application of such composition to a metal surface may be byroll-coating, spraying, dipping, doctoring, or other procedure at asuitable temperature for the particular application procedure in therange from 50400 F., elevated temperatures being employed to reduce theviscosity as needed for the particular application procedure employed.Residual heat in the applied coating is permitted to dissipate byradiation at ambient temperature.

Mineral oil.An effect of this material is to insolubilize the film andthus render it compatible with zinc-rich primer paints. This makes itpossible to pain fabricated components, without the necessity ofcleaning the film of the invention from such components prior topainting. It should be pointed out at this time that, by the presentinvention, the intrinsic salt spray resistance of the zincrich primerpaints is not in the least affected by the coatings of the presentinvention. In fact, the present coatings preserve the nascent or rawstate of the metal surface as it comes from the strip mill to theprocessor for fabrication by deep-draw operation or the like. Thus, theadherence of the subsequently applied primer paint is substantiallyincreased over application of such material to a partially oxidizedsurface that may have been exposed to the atmosphere prior toapplication of the primer paint.

The hydrocarbon or mineral oil set forth in the prior examples is apreferred component to be used in accordance with the present invention,primarily because of its low cost, ease of quality control, and readyavailability in quantity. This material may have a viscosity in therange of from about 1500 to 10,000 Saybolt Universal Seconds at 100 F.The lubricating qualities of the films of the invention increase withincreasing viscosity of the oil phase. Localized hot spots which mayoccur on drawdies in deep-drawing operations are known to cause failureof a lubricant film. The more viscous materials are desirable,therefore, because they are less sensitive to this temperature effect.The indicated upper viscosity limit of 10,000 S.U.S. at 100 F. is basedonly on problems encountered in application of the materials ofinvention. In the present invention, therefore, the lower limit is morecarefully guarded to assure a safety factor, as required of materialscapable of operating at elevated temperatures under high deep-drawingpressures.

Within the scope of the invention, a compounded vehicle, such as lighterweight oil containing an additive resin to increase the viscosity, canbe employed. Specific component materials within this category that havebeen successfully used are as follows:

Piccopale 70 (a non-registered mark designating a product of thePennsylvania Industrial Chemical Corporation). This is a hydrocarbonresin with a color of 6-10 on the Gardner scale. The material isavailable in solid, flaked, and solution form. It is soluble in allaliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons,naval stores, most esters, ethers, and ketones, and some alcohols.

Stikvel W (a product of the Velsicol Chemical Corporation) is alsoapplicable.

In some instances, a hydrogenated or bodied vegetable oil can be used asthe vehicle of the present invention. Also esterified acids as used inthe paint and varnish industry can be used.

The organic amine soaps: These materials can be prepared from any of thewater-soluble alkanol amines and a fatty acid with a titer not exceeding30 C. The titer of a soap may be defined as the solidifying point of thefatty acids liberated from a fat. The determination of this point bymelting the acids in a tube and noting the temperature at which theysolidify again on cooling is called the titer test.

The amine soaps used in accordance with the present invention can beprepared using conventional soap-forming fatty acids having titers belowabout 30 C. These fatty acids may be mixtures of fatty acids derivedfrom various oils, such as vegetable oils. For example, the acidmixtures derived from castor, coconut, palm kernel, linseed, olive,peanut, rapeseed, corn, and soya bean oils are suitable. Also suitableare the individual acids, such as oleic acid, ricinoleic acid, etc.,which have been separated from fatty acid mixtures suchas thosementioned above. In addition, fatty acids such as tall oil, which areformed as by-products from the manufacture of chemical wood pulp, can beused.

The amines, which are reacted with the low-titer fatty acids to form theamine soaps, may be any of the watersoluble, organic amines havingboiling points above about 100 C., for example: ethylene diamine,monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, monoisopropanol amine, morpholine, and 2-amino-1-butanol.Particularly advantageous for use in high speed roller coating processesare coating compositions in which the amine soap is made with aminessuch as 2-amino-2-methyl-l-propanol; 2-amino-2-methyl-1,3-propanediol;and 2-amino-2-ethyl-1,3-propanediol.

The coatings of the invention may be modified by the incorporation ofselected materials. Thus, where the coated sheets are to be stacked fora period of time prior to fabrication, it may be desirable toincorporate an antiblocking agent in the composition to minimize thesticking of one sheet to another. Suitable anti-blocking agents arethose which are compatible with the coating compositions but whichmigrate to the surface of the coating to form a tack-free superficialfilm upon drying of or congealing of the film. An example is methylcellulose and/ or polyvinyl alcohol, when used in amounts by weight offrom about -15% on an anhydrous basis.

The coating compositions of the invention also may be modified, ifdesired, by the addition of small amounts of other materials known toimprove the drawing qualities of lubricants. These may includewater-insoluble materials such. as chlorinated oils, flowers of sulfur,colloidal graphite etc.

The compositions can be additionally compounded with water as a carrier,for application. When so operating, of course, the water must be removedafter application, as by oven drying which has been common with aqueouscoating materials of the past. This may be considered by somepractitioners as a less desirable manner of operation than has beenpreviously described relative to application of the coatings ofinvention in neat or non-aqueous form.

In the appended claims, it is not intended that the presence ofmodifying agents or materials, such as those suggested above, beexcluded by defining the compositions as consisting essentially ofspecified components.

The selection of a particular coating composition in accordance with thepresent invention is primarily dependent upon the fabricating operationwhich is subsequently to be performed on the metal, the deciding factorbeing the magnitude of the coefficient of friction between the workpieceand the tool used in the shaping thereof. One method for evaluating thislubricant property is described in an article entitled Sliding FrictionTest for Metalworking Lubricants by W. J. Wojtowicz, published in theMay and June, 1955 issues of Lubrication Engineering. For moderate metaldrawing operations, lower soap contents may be used in the compositionsof the invention within the range indicated above.

Film thickness ranges as used in the present invention can be defined intwo ways, to wit:

(1) The films are applied in a thickness range of to 200 milligrams persquare foot of metal surface.

(2) Stated in terms of thousandths of an inch thickness, these willgenerally be in the following ranges, depending upon the severity of themetalworking operations to be encountered. The optimum coating thicknessdepends upon the gauge of the workpiece and the severity of the workingoperation, with heavier coatings being used for more difficultoperations. Generally, coatings having a thickness in the range of0.00003 to 0.001 inch are preferred. A good general average coatingthickness for most metalworking operations is .0001 inch.

The compositions of the invention are applicable to the following metalsurfaces:

(a) Plain cold-rolled steel, having a brushed, polished or other surfacethereon to be protected;

(b) Stainless steel in various degrees of surface finish;

(0) Aluminum;

(d) Magnesium;

(e) Brass and the like.

As indicated above, the workpieces or strip stock can be polished to ahigh lustre before the coating is applied, because these surfacefinishes are protected during subsequent handling, storage, andmetalworking operations.

ADVANTAGES OF COMPOSITIONS AND COATING The lubricating and protectivefilms of the invention are readily compatible with many other dielubricants.

A particular advantage of the films produced by the present invention isthat they do not contain any alkali soaps. Such are known to seriouslydetract from the salt spray resistance of a composite lubricant-Zincprimer film. Therefore, by the absence of such materials fromcompositions of the present invention, the salt spray resistance ofzinc-primer films is not weakened in the least. Currently used oil filmsare unsatisfactory in this respect because they do contain more than 5%of sodium or potassium soap. On the other hand, the pure organic aminesoap-mineral oil compositions of this invention provide excellentcompatibility without detracting from the salt spray resistance of zincprimer films.

Cleaning the films of the present invention from a coated workpieceafter its fabrication is not necessary, particularly where paintedsurfaces are to follow. However, if this is for some reason required, aswhere a previously polished surface has been protected and is to beexposed in final application, cleaning can be eadily performed. This isaccomplished by conventional cleaning equipment already widely employedin connection with metal drawing operations. Thus, a combination ofbrushes with a hot spray or bath of cleaning solution, such as aqueousalkali, emulsion cleaners, acid phosphate cleaners, and vapordegreasers, will be found operable.

A further advantage of the formulations ofthe invention is that theyresemble in physical properties many of the previously used materialsfor the same purposes. Thus, equipment in existence can be used withoutmodification or without substantial alteration, except, of course, forshutting down the drying ovens that probably are existent therein, fromthe use of the prior aqueous base materials.

APPLICATION OF COMPOSITIONS Because the compositions of invention havean oil-like base, it will follow that they have a substantial degree ofcompatibility with oily protective coatings (mill oil), commonly appliedto strip steel at the finishing mill. Therefore, due to this oilcompatibility, it is not necessary that the metal surface be renderedabsolutely oil-free prior to application of the present compositionsthereto. If the surface of the metal contains large amounts of oil, thesurface should be at least squeegeed or wiped to remove any excess priorto application of the coating composition. The metal surface is thenready for application in accordance with the present invention.

(II) Application When treating strip stock, roll coating is highlydesirable because the roll coater can operate in a heated bath of thematerial and pick up an appropriate load for application and thuscontrol the thickness of film applied. A further advantage of rollcoating is that it provides a method of applying the compositions of theinvention without removing the prior protective oil film, and yet theapplication is of such nature that a tightly adherent lubricant filmresults when the present compositions are applied. As the roll appliesthe coating to the metal surface, it breaks through the existing oilfilm and mixes the oil and the coating composition in intimatecombination. The coating composition, in turn, takes up the residual oiland makes it an integral part of the ultimate coating so that it willnot interfere with the adhesion of the coating to the strip, as byacting like a parting material.

The thickness of the film applied to the strip is governed by control ofthe aplication viscosity or temperature of the composition at the pointof application.

Although the compositions of the invention are particularly adapted foruse in roller coating operations, they also provide several advantageswhen employed in other methods of coating, such as spraying or dipping.In general, the viscosity of the compositions, .or temperature, will bevaried to place them in a compatible range with the coating methodemployed. As an example, when used in the roller coating process,viscosities in the range of 1500 to 5000 S.U.S. at the temperature ofapplication will generally be applicable. This generally connotes atemperature of application of from 150 to about 300 F. In the case ofdip-coating, viscosities will generally be retained in the slightlylower range of 1500 to 2000 S.U.S. To effect these viscosities,application temperatures are approximately 200 to 250 F.

For spraying operations, it is not desired that the coating be heatedbecause of the difficulty of retaining it in such condition as it passesthrough the lines, orifices,

nozzles, and the like. Therefore, the naturally lower vi's the method ofapplying the composition and by varying the viscosity of the compositionat the situs of application; the greater the viscosity, the thicker theapplied coating will be.

Relative to application, it is important where a surface is notchemically clean, as where it might contain a residualcorrosion-protecting oil film, to press physically the composition intointimate contacting relationship with the surface to provide a tightbond. Thus, it can be said that the coating composition is physicallyadmixed with any residual oil film on the surface of the metal.

(III) Exposure to ambient temperature The composition and the metal arethen exposed to ambient temperature so that the heat of the coating, ifany, can be dissipated.

(IV) Subsequent processing After the coatings of invention are applied,that is, immediately after drying or setting, the coated workpiece canbe cold-worked by any usual procedure such as deepdrawing, shearing,form-rolling, and the like.

While cold-Working metal workpieces, which is to be understood asincluding blanking, piercing, cutting, and perforating, the coatingshave special value in that they effectively protect the tools or diesused to fabricate the workpiece, as well as the coated surfaces of themetal workpiece.

ADVANTAGES OF THE INVENTION From the foregoing, it can be understoodthat several advantages arise from the use of the present invention. Oneis that, particularly when using the roller coating applicationtechnique, the metal sheets do not have to be chemically clean forsatisfactory operation. This is in direct contrast to the old drylubricant coating processes where it was not only necessary tothoroughly clean the sheets prior to coating, but also to make sure thatany cleaning agent on the sheets was removed prior to application of thedry coating.

Thus, all alkali washing materials, phosphates, tanks and the like arereplaced perhaps by a simple swab or equivalent wiping device.

Another advantage flowing from the invention of particular importance isits application in highly automated production lines in which metalsheets or continuous strips are moved substantially continuously at arelatively high rate of speed from a supply point or reel and through acoating, drying, and single or plural-stage fabricating operation, allwithout marring the surface finish previously applied to the strip atthe finishing mill.

A further advantage of the present invention resides in the fact thatdrying of the applied coating, as by heating in an oven or the like, isnot required. It will be observed that substantial reduction in expenseis encountered by so operating. Both the cost of the fuel to fire suchan oven and the capital investment of the oven are obviated.

A further advantage is that substantially reduced plant areas ofoperation are required for effecting the present invention because ofthe omission of the following components from a floor space area:

(a) Precleaning equipment, which is either eliminated or substantiallyreduced in physical size to a wiping squeegee and collection tank forexcess mill oil wiped from the workpiece; and

(b) The oven and the associated fueling system therefor.

, Since the process of the invention is readily integrated into existingequipment, generally by the mere closing down or removal of thepre-cleaning and oven compo nents thereof, metal fabricators can effectan immediate savings in their operations and produce better productsbecause of the inherent advantages of the films of invention.

From the foregoing, it will be understood that the present inventionprovides coatings, compositions, and a process for effectivelyprotecting finished metal work surfaces prior to and during cold workingoperations with a high degree of flexibility for adapting the inventionto a variety of metalworking operations and metals to be worked, and forintegrating the process of the invention into existing production lineswith minimum modification of existing equipment.

What is claimed is:

1. A coating composition consisting essentially of the followingingredients blended in the range of proportions indicated:

Ingredient: Parts by weight Lubricating oil, 1,50010,000 S.U.S. at

100 F 3475 Water-soluble organic amine soap of low titer fatty acid66-25 2. A coating composition according to claim 1 in which thelubricating oil is a mineral oil.

3. A coating composition according to claim 1 in which the lubricatingoil is a vegetable oil.

4. A coating composition according to claim 1 in which the soap-formingorganic amine is a water-soluble aliphatic amine.

5. A coating composition according to claim 1 in which the soap-formingorganic amine is a Water-soluble alkanol amine.

6. A coating composition according to claim 1 in which the soap-formingorganic amine has a boiling point above about 100 C.

7. A metal workpiece having on its surface a coating of a compositionconsisting essentially of the following ingredients blended in the rangeof proportions indicated:

Ingredient: Parts by weight Lubricating oil, 1,50010,000 S.U.S. at

100 F. 34-75 Water-soluble organic amine soap oflow titer fatty acid66-25 said coating being present in the amount of about 100- 200milligrams per square foot of metal surface area.

8. A coated metal workpiece according to claim 7 in which thelubricating oil of the coating composition is a mineral oil.

9. A coated metal workpiece according to claim 7 in which thelubricating oil of the coating composition is a vegetable oil.

10. A coated metal workpiece according to claim 7 in which thesoap-forming organic amine is a watersoluble aliphatic amine.

11. A coated metal workpiece according to claim 7 in which thesoap-forming organic amine is a watersoluble alkanol amine.

12. A coated metal workpiece according to claim 7 in which thesoap-forming organic amine has a boiling point above about 100 F.

13. The method of forming a lubricant coating over an oil-coated surfaceof a metal workpiece comprising the steps of wiping any excess oil fromsaid surface as required to leave only a thin film thereof, applyingover said thin oil film a coating composition consisting essentially ofthe following ingredients blended in the range of proportions indicated:

Ingredient: Parts by weight Lubricating oil, 1,500-10,000 S.U.S. at

F 34-75 Water-soluble organic amine soap of low titer fatty acid 6625and physically pressing said coating composition into intimatecontacting relationship with said thin oil film to effect integration ofthe latter with the coating composition and bonding of the resultingintegrated composition to the metal surface.

14. The method of forming a lubricant coating according to claim 13, inwhich method said coating composition is applied in a heated conditionat a temperature in the range of 50350 F. and, after its application, iscooled by exposure to ambient temperature.

15. In the processing of a metal workpiece to form a fabricated article,the steps of (a) Applying to a surface of a workpiece an adherent filmof a metalworking lubricant consisting essentially of the followingingredients blended in the proportions indicated:

Ingredient: Parts by weight Lubricating oil, 1,500-l0,000 S.U.S. at

100 F. 34-75 Water-soluble organic amine soap of low titer fatty acid66-25 (b) Deforming the coated workpiece between metalworking dies whilesaid adherent film serves as a lubricant between the workpiece and thedies; and

(0) Without removing residual amounts of said adherent film remaining onthe deformed workpiece, completing the fabricated article by performingfinishing operations thereon.

16. In the processing of a metal workpiece to form a fabricated article,the steps of claim 15, wherein a primer paint coating is applied to thedeformed workpiece as a finishing operation without first removingresidual amounts of said adherent film from the deformed workpiece.

17. In the processing of a metal workpiece to form a fabricated article,the steps of claim 16 wherein the primer paint is a zinc primer paint.

18. In the processing of a metal workpiece to form a fabricated article,the steps of claim 15 wherein a Welding operation is performed on thedeformed workpiece as a finishing operation without first removingresidual amounts of said adherent film remaining on the deformedworkpiece.

References Cited UNITED STATES PATENTS 2,520,356 8/1950 Bishop 1l7-134 X2,774,684 12/1956 Fucinari 117-134 X 2,966,425 12/1960 Fucinari et al.117-134 X 2,976,179 3/1961 Westlund ll7l34 X RALPH S. KENDALL, PrimaryExaminer. ALFRED L. LEAVITT, Examiner.

